The applicant requests support from a NINR Ruth L. Kirschstein National Research Service Awards for Individual Predoctoral Fellows in Nursing Research (F31) to examine chronic pain following trauma. Chronic pain is a significant public health problem affecting one third of the U.S. adult population with a considerable economic and personal burden. Trauma is a major source of chronic pain; trauma patients report high rates of physical disability, post-traumatic stress disorder, missed days of work, increased healthcare encounters, anxiety, and depression. High pain intensity at the time of trauma has been identified as a risk factor for chronic pain, but the precise level of minimum pain intensity or severity of unrelieved pain that leads to chronic pain is unknown. Furthermore, the incidence of pain hypersensitivity in trauma patients after recovery from the injury is not well documented. The purpose of this study is to test whether unrelieved post-trauma pain is associated with chronic pain and pain hypersensitivity to subsequent painful stimuli following lower extremity trauma. The proposed study will: (1) identify and describe how pain threshold, duration, and timing effects at time of traumatic injury are associated with chronic pain following lower extremity trauma and, (2) test whether neuronal changes from central sensitization are present in this population. Aim 1 will examine how unrelieved acute pain after lower extremity trauma correlates with chronic pain by a retrospective review of medical records of adult trauma patients to examine patterns, intensity of pain ratings, and analgesic use during hospitalization after injury. For Aim 2, a subset of participants from Aim 1 will be classified into one of four groups based on the mean pain score during the first 24 hours of hospital admission: (1) mean pain score <2, no chronic pain, (2) mean pain score >2, no chronic pain, (3) mean pain score <2, chronic pain, (4) mean pain score >2, chronic pain. A group of age/gender-matched trauma-naive participants will be included as normative controls. Assessments for central neuronal plasticity changes due to central sensitization will be completed: Quantitative Sensory Testing to measure pain hypersensitivity, Current Perception Threshold testing to measure sensory fiber function, Conditioned Pain Modulation to assess diffuse noxious inhibitory control, and Pressure Pain Threshold to assess mechanical pain sensitivity. The training outlined in this proposal will augment previous training initiated by the applicant in her goal to become an independent nurse scientist with a research program focusing on underlying biological mechanisms associated with chronic pain. Chronic pain research aligns well with the NINR mission to identify underlying biological bases of symptoms (e.g., pain) that interfere with patient quality of life. Training wil focus on: (1) increasing the applicant's knowledge base of pathophysiology of chronic pain; (2) enrich her methodological and analytical skills related to clinical research, and (3) successful dissertation defense and improved grant and manuscript writing skills. Study findings may contribute to development of new therapeutic strategies to decrease chronic pain.